A process has been proposed recently in which a heavy petroleum oil (such as heavy oil, asphaltene-containing material, etc.) is cracked into pitch and an oil component by subjecting the heavy petroleum oil to the thermal cracking treatment in a reactor. In such process, a thermally cracked gas (cracked oil and gas) is released in the form of vapors from the top of the reactor, and naturally, pitch (in the form of droplets) is entrained in the flow of the thermally cracked gas.
Heretofore, in order to remove such pitch from the thermally cracked gas thus released, it has been general practice to pass the thermally cracked gas through an apparatus such as venturi scrubber or cyclone to catch and collect the pitch component in the apparatus. According to such system, however, it is extremely difficult to reduce the amount of pitch contained in the thermally cracked gas to a satisfactorily low level, for example not more than 500 ppm.